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Development and testing of a high sensitivity monitor for the measurement of Total Organic Carbon (TOC) in water without gravity-dependent components and using minimal chemical reagents has been performed. A breadboard instrument was constructed and tested for linearity, selectivity, and day-to-day reproducibility. The instrument has a linear response for a wide range of organic compounds over a range from 20 ppb C to 50 ppm C, with excellent day-to-day reproducibility. The upper level can be extended to ∼100 ppm C by changing the operating conditions of the analyzer. The selectivity of the instrument has been determined and no interference is observed except for high concentrations (> 10 ppm) of iodine, hypochlorous acid, sodium nitrite and sodium sulfide.

An approach to the isolation and concentration of volatile organic compounds from a water sample prior to chemical analysis in a microgravity environment has been previously described (Reference 1). The Volatile Organics Concentrator (VOC) system was designed for attachment to a gas chromatograph/mass spectrometer (GC/MS) for analysis of the volatile organics in water on Space Station Freedom. The VOC concept utilizes a primary solid sorbent for collection and concentration of the the organics from water, with subsequent transfer using nitrogen gas through a permeation dryer tube to a secondary solid sorbent tube. The secondary solid sorbent is thermally desorbed to a gas chromatograph for separation of the volatiles which are detected using a mass spectrometer.